This invention relates to an improvement in hair treatments in which moistened hair is placed on rollers or rods (hereinafter "rollers"), hair protein disulfide bonds which cross-link the hair are broken by use of thiol-containing reagents, and then the disulfide bonds are reformed by use of an oxidizing neutralizer which causes the hair to acquire a new curl. The improvement of our invention involves the use of a bisulfite or sulfite containing aqueous solution which is applied to the hair prior to wrapping the hair on the rollers.
Thiol-containing reagents for hair treatments are those materials which contain a free --SH group or mercaptan. Salts of thioglycolate acids and thioglycolic acid esters are the reagents which are normally used in such hair treatments. Other thiol-containing reagents such as thiolactic acid, .beta.-mercaptopropionic acid, .beta.-mercaptobutyric acid, and the like are known in the art to be effective.
While hair treatments with thiol containing reagents used in conjunction with hair rollers are most frequently used for waving hair, i.e., putting in curl, these reagents may be used with rollers for straightening hair, i.e., taking some curl from curly hair. When a tight curl is wanted as in waving, curlers of a narrow diameter, such as about 1 cm or less, are used. For straightening, curlers of a wide diameter, such as about 5 cm, may be used. The improvement of this invention relates to both waving and straightening hair, although its primary uses will probably be in the field of hair waving. For convenience, the word "waving" is used hereinbelow to mean hair treatments which include both waving and straightening. Thus, those methods for imparting a tighter curl when a narrow diameter roller is used will also impart a looser curl when a wide diameter roller is used.
The process of waving hair is old in the art and will not be explained in detail herein. Generally, in such processes, dampened hair is wound about a roller or curler and clamped in place. A solution containing the mercaptan reagent (waving lotion) is then applied to the hair upon the rollers to cleave the disulfide bonds within the hair. After waiting a suitable period of time, the waving lotion is rinsed from the hair. The hair is then neutralized with an oxidizing reagent which reforms disulfide bonds within the hair that had been broken by the thiol-containing reagent. It is believed that the reformation of the disulfide bonds within the hair is what causes the new wave or curl to be imparted to the hair. The curls so imparted will not wash out with water and consequently a curl or wave so formed is called a permanent wave. When this process is carried out at room temperature, without the use of external heating devices, it is called "cold waving."
Modern, commercial, cold, permanent waving preparations frequently include an instruction to wet the hair with the waving solution or lotion prior to wrapping the hair upon the rollers. It has been found that such a prewrap treatment helps impart a tighter curl to the hair than if water, alone, is used to wet the hair prior to wrapping. A problem with such a prewrapping procedure however, is that although manufacturers suggest that gloves be worn during the wrapping procedure, the person, such as the hair dresser, who would do the wrapping usually finds that the use of gloves makes such wrapping quite difficult and cumbersome to achieve. As a consequence of this difficulty, many such users do not wear gloves during the wrapping process. Frequent and/or prolonged contact of the user's hands with the waving solution and its thiol containing reagent often causes skin irritation and in some cases causes allergic reactions. This is true even where the safest thiol-containing reagents, such as thioglycolic acid derivatives, are used. Thus, the hair dresser is frequently faced with the problems of getting a loose curl when a tight curl is desired because a prewrap solution of water was used rather than waving lotion, or of getting irritated skin from handling the waving lotion without gloves.
While the general cold waving process is old in the art, there has been an evolution in the pH and constituents of the waving lotion. As originally introduced, the waving lotion pH was approximately 9.2 or higher. More recently cold waving has been practiced at a pH as low as about 7.6. Still more recently so-called "acid" waving has been introduced. The pH of an acid waving solution is approximately 6.9 or lower. While the principal waving constituent in the older waving lotions was a salt of thioglycolic acid, such as ammonium thioglycolate, the acid waving lotions usually contain glyceryl monothioglycolate as the principal active ingredient.
While there are several advantages to using an acid waving system, there are also disadvantages. One important disadvantage to these systems is that they are more injurious to skin than were the more basic ammonium thioglycolate based, waving lotions. Consequently, most manufacturers do not suggest using the acid waving lotion as a prewrap solution because it is known that some users don't wear gloves during the wrapping step. With no prewrapping solution or, in effect, a water prewrapping solution, curl tightness often suffers.
One benefit of our invention is to lessen the contact of the mercaptan-containing reagent with the user's hands by providing an alternative prewrap solution which does not contain a mercaptan reagent.
Another benefit of our invention is to provide a prewrap solution which will allow the formation of a tighter curl than is possible by using only water as the prewrap solution.